| TO: | Adam Blalock, FDEP | |||||
| Mary Walker, US EPA Region 4 | ||||||
| FROM: | Ed Sherwod, TBEP Executive Direcory (NMC Facilitator) | |||||
| DATE: | 2020-04-28 | |||||
| SUBJECT: | 2019 Tampa Bay Nutrient Management Compliance Assessment Results | |||||
| cc: | Jessica Mostyn, Erin Rasnake, Ben Salys, Kevin O’Donnell, Julie Espy, Daryll Joyner (FDEP Tallahassee) | |||||
| Ramandeep Kaur, Vishwas Sathe, Amaury Betancourt, Anthony Annibali, Edgar Guerron-Orejuela (FDEP Tampa) | ||||||
| Anne Heard, Felicia Burks, Mark Nuhfer, Tom McGill (EPA Region 4) | ||||||
| Jeff Greenwell, Santino Provenzano, Tony Janicki, Ray Pribble (TBNMC) | ||||||
| Ed Sherwood, Maya Burke, Marcus Beck (TBEP) | ||||||
| Assessment Step | Result | Action |
| I. Determine annual bay segment specific chlorophyll-a FDEP threshold attainment as traditionally assessed using the Decision Matrix management strategy developed by the TBEP (Janicki, D.Wade, and Pribble 2000). | Yes | NMC Action 1 |
| No | NMC Action 1 | |
| II. Review data and determine if an anomalous event(s) influenced non-attainment of the bay segment specific chlorophyll-a threshold. | Yes | NMC Action 2 |
| No | Go to III | |
| III. Determine if the chlorophyll-a thresholds have been exceeded for <2 consecutive years. | Yes | NMC Action 2 |
| No | Go to IV | |
| IV. Determine if the bay segment specific federally-recognized TMDL has been achieved using the hydrologically-adjusted compliance assessment outlined in NMC Decision Memo #11 (Appendix 2-11). | Yes | NMC Action 3 |
| No | Go to V | |
| V. For a given year or for multiple years, compile and report entity-specific combined source loads in comparison to 5-yr annual average reasonable assurance allocation. | Compile & Report | NMC Action 4 |
NMC actions outlined in Figure 1 and Table 1 performed during RA Implementation Period (2017-2021) are as follows:
| NMC Action 1 - | A report assessing attainment of bay segment specific chlorophyll-a thresholds using the EPCHC dataset, as traditionally assessed using the Decision Matrix management strategy developed by the TBEP (Janicki, D.Wade, and Pribble 2000) will be delivered to FDEP and EPA (this report). |
| NMC Action 2 - | A report of the anomalous event(s) or data which influenced the bay segment chlorophyll-a exceedence will be delivered to FDEP and EPA, upon review by NMC participants (this report). |
| NMC Action 3 - | Consider re-evaluation of the bay segment assimilative capacity based on nonattainment of bay segment chlorophyll-a threshold while meeting federally-recognized TMDL. |
| NMC Action 4 - | If federally-recognized TMDL not achieved, compile results of hydrologic evaluation for FDEP’s review and identify potential further actions needed to achieve reasonable assurance for bay segment allocations. |
Results from 2019 indicate that all RA bay segments, excluding Old Tampa Bay, met chlorophyll-a thresholds accepted by the FDEP to maintain FDEP Reasonable Assurance for Tampa Bay and to comply with the EPA TMDL (Figure 2) and estuarine numeric nutrient criteria for Tampa Bay (EPA Approval Letter Nov. 30, 2012). In Old Tampa Bay, chlorophyll-a concentrations were elevated in a poorly flushed region that has typically produced summertime blooms of Pyrodinium bahamense since 2009 (Figure 3; Note that individual station exceedences are not considered in this RA compliance assessment). This observation is reflected in the majority of summertime months with chlorophyll-a concentrations higher than long-term median values in Old Tampa Bay (Figure 4). In response, the Consortium formed an Old Tampa Bay Working Group in early 2020 to prioritize additional investigations and future management actions that may alleviate the conditions fostering these summertime blooms. Additionally, the Consortium is proactively developing loading information for the 2018-2019 period to assess any anomalous conditions.
The TBEP, in partnership with the Southwest Florida Water Management District, has previously developed an integrated ecosystem model to evaluate the net environmental benefits that may result from implementing various management actions in Old Tampa Bay including: reducing point sources, nonpoint sources, and causeway obstructions in Old Tampa Bay (Sherwood et al. 2015). Furthermore, the TBEP is funding research conducted by the Florida Fish and Wildlife Research Institute to improve understanding of the cell physiology and behavior of Pyrodinium bahamense and evaluate the potential for using shellfish to mitigate these algal blooms in Old Tampa Bay. Elevated chlorophyll-a concentrations were also observed in Lower Tampa Bay during August 2019, primarily as a result of Bacillariophyta and Pseudo-nitzschia (diatoms) blooms (Figure 7). Monthly chlorophyll-a conditions in Hillsborough Bay and Middle Tampa Bay were largely within or below median historic ranges during 2019 (Figure 4). Finally, a water quality dashboard (https://shiny.tbeptech.org/wq-dash) was developed to synthesize the data, assess additional water quality metrics (phytoplankton counts), and inform Consortium participants and other resource managers on the status of water quality in Tampa Bay. The dashboard will allow for enhanced adaptive management response by the community in the future.
Seagrasses remain relatively stable given overall improved water quality conditions within Tampa Bay. Aerial photographs taken in December 2017 - January 2018 indicate that seagrass coverage decreased by 1,004 acres baywide over the 2016 estimate, but still exceed the TBEP’s recovery goal and total 40,652 acres (Figure 5). Seagrass acreage showed the greatest decreases in Hillsborough Bay (-544 acres) and Old Tampa Bay (-406 acres). The greatest increases were observed in Boca Ciega Bay (+134 acres) and Lower Tampa Bay (+156 acres) over the 2016 to 2018 period. The next SWFWMD seagrass coverage estimate will be developed from aerial photographs acquired over the winter 2019-20 period.
Detailed results for the 2017-2021 RA implementation period are also provided in Tables 2, 3, 4, and 5 for each bay segment. As of the 2019 reporting period, NMC Actions 2-5 are not necessary based upon observed water quality and seagrass conditions within Tampa Bay. Individual annual reports of the bay’s conditions from 2017 – 2019 can be found on the TBEP Tech website, as specified in the following links (Sherwood and Raulerson 2018; Burke and Raulerson 2019; Beck, Burke, and Raulerson 2020). A summary of historic attainment of the regulatory chlorophyll-a thresholds for each of the bay segments is depicted in Figure 6.
Lastly, annual hydrologic conditions within all four bay segments in 2019 were estimated to exceed 1992-1994 levels. Therefore, hydrologic adjustments for evaluating compliance with load allocations/permitting targets should be applied for the Old Tampa Bay, Hillsborough Bay, Middle Tampa Bay, and Lower Tampa Bay segments (Janicki Environmental, Inc. 2012, 2016). The estimated hydrologic loads for each bay segment relative to observed 1992-1994 levels are indicated in the table below. The associated compliance load adjustment factors (if applicable) are also specified. A tool to calculate the hydrologic estimates and adjustment factors by bay segment is now available online through an interactive dashboard (https://shiny.tbeptech.org/tbnmc_hydrologic_estimates/).
Figure 2: Historic chlorophyll-a annual averages for the four major bay segments of Tampa Bay. Annual averages in 2019 were below the regulatory thresholds developed under the Tampa Nitrogen Management Consortium’s nutrient management strategy in three of four bay segments, excluding Old Tampa Bay. Vertical grey lines indicate the start of the 2017-2021 Reasonable Assurance compliance assessment period Data source: EPCHC.
Figure 3: Map depicting individual station chlorophyll-a exceedences in Tampa Bay relative to FDEP regulatory thresholds for chlorophyll-a. Note individual station exceedences do not indicate failed compliance at the bay segment scale.
Figure 4: 2019 monthly chlorophyll-a bay segment means (red dots) compared to monthly distributions from 1972-2018 (box plots and black dots). Boxes encompass the 25th and 75th percentiles, while whiskers bound the interquartile range. Dots beyond the whiskers represent outliers throughout the 1972-2018 sample period.
Figure 5: Historic seagrass coverage estimates for Tampa Bay. Data source: TBEP & SWFWMD.
Figure 6: Attainment of adopted chlorophyll-a thresholds (1974 - 2019) in the four major bay segments. Green (yes) indicates that average annual chlorophyll-a thresholds were met; red (no) indicates that threshold levels were not met. Grey line is the beginning of the Reasonable Assurance implementation period. Data source: EPCHC.
Figure 7: Observed phytoplankton cell counts for July in Old Tampa Bay (top) and August in Lower Tampa Bay (bottom). The count data represent sums across segment stations for different phytoplankton taxa. Data source: EPCHC.
| Bay Segment Reasonable Assurance Assessment Steps | DATA USED TO ASSESS ANNUAL REASONABLE ASSURANCE | OUTCOME | ||||
| Year 1 (2017) | Year 2 (2018) | Year 3 (2019) | Year 4 (2020) | Year 5 (2021) | ||
| NMC Action 1: Determine if observed chlorophyll-a exceeds FDEP threshold of 9.3 ug/L | 9.5 (Yes) | 9.2 (No) | 9.8 (Yes) | First and third years (2017 & 2019) above threshold, not necessary for NMC Actions 2-5. | ||
| NMC Action 2: Determine if any observed chlorophyll-a exceedences occurred for 2 consecutive years | No | No | No | Concurrent years with threshold exceedances did not occur, not necessary for NMC Actions 3-5 | ||
| NMC Action 3: Determine if observed hydrologically-normalized total load exceeds federally-recognized TMDL of 486 tons/year | N/A | N/A | N/A | Not necessary due to observed water quality and seagrass conditions in the bay segment | ||
| NMC Actions 4-5: Determine if any entity/source/facility specific exceedences of 5-yr average allocation occurred during implementation period | Not necessary when chloropyll-a threshold met | |||||
| Bay Segment Reasonable Assurance Assessment Steps | DATA USED TO ASSESS ANNUAL REASONABLE ASSURANCE | OUTCOME | ||||
| Year 1 (2017) | Year 2 (2018) | Year 3 (2019) | Year 4 (2020) | Year 5 (2021) | ||
| NMC Action 1: Determine if observed chlorophyll-a exceeds FDEP threshold of 15 ug/L | 9.7 (No) | 13.9 (No) | 11 (No) | All years below threshold so far, not necessary for NMC Actions 2-5 | ||
| NMC Action 2: Determine if any observed chlorophyll-a exceedences occurred for 2 consecutive years | No | No | No | All years met threshold, not necessary for NMC Actions 3-5 | ||
| NMC Action 3: Determine if observed hydrologically-normalized total load exceeds federally-recognized TMDL of 1451 tons/year | N/A | N/A | N/A | Not necessary due to observed water quality and seagrass conditions in the bay segment | ||
| NMC Actions 4-5: Determine if any entity/source/facility specific exceedences of 5-yr average allocation occurred during implementation period | Not necessary when chloropyll-a threshold met | |||||
| Bay Segment Reasonable Assurance Assessment Steps | DATA USED TO ASSESS ANNUAL REASONABLE ASSURANCE | OUTCOME | ||||
| Year 1 (2017) | Year 2 (2018) | Year 3 (2019) | Year 4 (2020) | Year 5 (2021) | ||
| NMC Action 1: Determine if observed chlorophyll-a exceeds FDEP threshold of 8.5 ug/L | 5.8 (No) | 7 (No) | 5.7 (No) | All years below threshold so far, not necessary for NMC Actions 2-5 | ||
| NMC Action 2: Determine if any observed chlorophyll-a exceedences occurred for 2 consecutive years | No | No | No | All years met threshold, not necessary for NMC Actions 3-5 | ||
| NMC Action 3: Determine if observed hydrologically-normalized total load exceeds federally-recognized TMDL of 799 tons/year | N/A | N/A | N/A | Not necessary due to observed water quality and seagrass conditions in the bay segment | ||
| NMC Actions 4-5: Determine if any entity/source/facility specific exceedences of 5-yr average allocation occurred during implementation period | Not necessary when chloropyll-a threshold met | |||||
| Bay Segment Reasonable Assurance Assessment Steps | DATA USED TO ASSESS ANNUAL REASONABLE ASSURANCE | OUTCOME | ||||
| Year 1 (2017) | Year 2 (2018) | Year 3 (2019) | Year 4 (2020) | Year 5 (2021) | ||
| NMC Action 1: Determine if observed chlorophyll-a exceeds FDEP threshold of 5.1 ug/L | 3.3 (No) | 4.7 (No) | 3.9 (No) | All years below threshold so far, not necessary for NMC Actions 2-5 | ||
| NMC Action 2: Determine if any observed chlorophyll-a exceedences occurred for 2 consecutive years | No | No | No | All years met threshold, not necessary for NMC Actions 3-5 | ||
| NMC Action 3: Determine if observed hydrologically-normalized total load exceeds federally-recognized TMDL of 349 tons/year | N/A | N/A | N/A | Not necessary due to observed water quality and seagrass conditions in the bay segment | ||
| NMC Actions 4-5: Determine if any entity/source/facility specific exceedences of 5-yr average allocation occurred during implementation period | Not necessary when chloropyll-a threshold met | |||||
Beck, M., M. Burke, and G. Raulerson. 2020. “2019 Tampa Bay Water Quality Assessment.” 01-20. St. Petersburg, Florida: Tampa Bay Estuary Program. https://tbeptech.org/TBEP_TECH_PUBS/2020/TBEP_01_20_2019_Decision_Matrix_Update.pdf.
Burke, M., and G. Raulerson. 2019. “2018 Tampa Bay Water Quality Assessment.” 01-19. St. Petersburg, Florida: Tampa Bay Estuary Program. http://www.tbeptech.org/TBEP_TECH_PUBS/2019/TBEP_01_19_2018_Decision_Matrix_Update_FINAL.pdf.
Janicki, A., D.Wade, and J. R. Pribble. 2000. “Developing and Establishing a Process to Track the Status of Chlorophyll-a Concentrations and Light Attenuation to Support Seagrass Restoration Goals in Tampa Bay.” 04-00. St. Petersburg, Florida: Tampa Bay Estuary Program. https://tbeptech.org/TBEP_TECH_PUBS/2000/TBEP_04_00Chlor-A.pdf.
Janicki Environmental, Inc. 2012. “Development of a Screening Level Tool for Estimating Annual Hydrologic Loadings to Tampa Bay.” 05-12. St. Petersburg, Florida: Tampa Bay Estuary Program. https://tbeptech.org/TBEP_TECH_PUBS/2012/TBEP_05_12_NMC_Hyd_Tool_Report_052112.pdf.
———. 2016. “Update on the Development of a Screening Level Tool for Estimating Annual Hydrologic Loadings to Tampa Bay.” 03-16. St. Petersburg, Florida: Tampa Bay Estuary Program. https://tbeptech.org/TBEP_TECH_PUBS/2016/TBEP_03_16_TBNMC_Tech_Memo_Update_LTB_Hyd_Tool.pdf.
Sherwood, E., H. Greening, T. Janicki, and D. Karlen. 2015. “Development of an Integrated Ecosystem Model to Determine Effectiveness of Potential Watershed Management Projects on Improving Old Tampa Bay.” 10-15. St. Petersburg, Florida: Tampa Bay Estuary Program. https://tbeptech.org/TBEP_TECH_PUBS/2015/TBEP_10_15_OTB_IM_Summary_5thICRW.pdf.
Sherwood, E., and G. Raulerson. 2018. “2017 Tampa Bay Water Quality Assessment.” 01-18. St. Petersburg, Florida: Tampa Bay Estuary Program. https://tbeptech.org/TBEP_TECH_PUBS/2018/TBEP_01_18_2017_Decision_Matrix_Results_Update.pdf.